Fuel efficiency

I have an 06 Moomba Outback V, it has a little over 600 hours on it and it has been at least 2-3 years since it has had any maintenance other than oil changes. It seems like the boats fuel efficiency has been getting worse and worse lately, today about 8 gallons got about an hour of runs, there was not an absurd amount of stop and go driving I’d say an average amount. Does that not seem abnormal? I know I need a tune up and all but do the things a tune up cover really affect the millage that bad? Is there any other possible problems? Thanks for the help.

My Enzo started consuming more fuel than average so I replaces the distributer cap and rotor as well as the spark plugs and that took care of the excessive fuel consumption.

Do the tune up and see if the problem remains. Why wouldn't you?

I plan to do a tune up in the spring. I haven't yet because I am a student and have to wait to see how much money I have left from student loans. I assumed the tune up was the biggest factor I just wanted to make sure I haven't over looked anything else.

Thanks guys.

Glad to see your student loans are being put to good use. You should apply for some scholarship and grant money as well!

I've been trying to. got to pay for gas some how.

Depending on how much weight you're running 8 GPH doesn't sound crazy high. Do a tune up and see what it gets you. Fuel injection is more difficult to troubleshoot. I burn about 6 GPH in mine with an old carbed big block. Plugs wires cap and rotor are cheap so no reason not to try that first if it's never had it or been a while since last time. Also check your timing as part of the tune up

Fuel consumption wakeboarding behind an Epic 23V with the 8.1L is around 7 GPH.

Just to throw another reference point in...